There are many kinds of IC cards for data storage in the present market. For example: SIM card, SD card, MMC card, Memory Stick, Compact Flash card, XD card, PCMCIA card and Smart Media card . . . etc. They all communicate directly with the suitable main console through its internal interface. However, they do not communicate directly with general computers or other main units. Instead, they need an external card reader as a communication interface for retrieving or storing data. Most card readers available in the present market includes single unit or all-in-one unit are bulky and undesirable in portability. Their usability is not satisfactory.